Passengers stand on seats to avoid a rat in an A Train going into Brooklyn on Monday, April 7. (Credit: Jianis Ponnampadikkal Kader/YouTube)

NEW YORK (CBSNewYork) — Seeing a rat in the subway system is as common an experience for New Yorkers as seeing a taxi in Midtown, or a tree in Central Park.

But those rats are scurrying along the track beds and in and out of holes in the tile walls. When a rat ends up on a train, it is cause for alarm and terror even among the most grizzled New Yorkers.

On Monday, a rat found its way onto an “A” train heading from Manhattan to Brooklyn. A YouTube video showed passengers lifting up their legs and even standing up on the seats, and many of them screaming in horror.

Passenger Jianis Ponnampadikkal Kader, who posted the video Monday, said the rat boarded the train at the Fulton Street station in Lower Manhattan during the morning commute.

Kader wrote that someone getting off screamed, “Rat on the train!” But the doors closed, and by the time the passengers realized what was happening, they were trapped with the rat inside as the train entered the tunnel under the East River.